CVE-2021-47218

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This may then cause a NULL pointer dereference, since\nthe policydb code relies on the assumption that even after a failed\nhashtab_init(), hashtab_map() and hashtab_destroy() can be safely called\non it. Yet, these detect an empty hashtab only by looking at the size.\n\nFix this by making sure that hashtab_init() always leaves behind a valid\nempty hashtab when the allocation fails."}, {"lang": "es", "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: selinux: corregir la desreferencia de puntero NULL cuando falla la asignaci\u00f3n de hashtab Cuando la asignaci\u00f3n de la matriz de ranuras de la tabla hash falla en hashtab_init(), h->size se deja inicializado con un valor distinto de cero, pero el puntero h->htable es NULL. Esto puede causar una desreferencia de puntero NULL, ya que el c\u00f3digo policydb se basa en la suposici\u00f3n de que incluso despu\u00e9s de un hashtab_init() fallido, se pueden llamar hashtab_map() y hashtab_destroy() de forma segura. Sin embargo, estos detectan un hashtab vac\u00edo solo mirando el tama\u00f1o. Solucione esto asegur\u00e1ndose de que hashtab_init() siempre deje atr\u00e1s un hashtab vac\u00edo v\u00e1lido cuando falla la asignaci\u00f3n."}], "id": "CVE-2021-47218", "lastModified": "2026-06-17T04:16:56.023", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 5.5, "baseSeverity": "MEDIUM", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "version": "3.1"}, "exploitabilityScore": 1.8, "impactScore": 3.6, "source": "nvd@nist.gov", "type": "Primary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2021-47218", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "total"}], "role": "CISA Coordinator", "timestamp": "2024-04-15T15:01:50.328604Z", "version": "2.0.3"}}]}, "published": "2024-04-10T19:15:48.860", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/83c8ab8503adf56bf68dafc7a382f4946c87da79"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/b17dd53cac769dd13031b0ca34f90cc65e523fab"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/dc27f3c5d10c58069672215787a96b4fae01818b"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/83c8ab8503adf56bf68dafc7a382f4946c87da79"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/b17dd53cac769dd13031b0ca34f90cc65e523fab"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/dc27f3c5d10c58069672215787a96b4fae01818b"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-476"}], "source": "nvd@nist.gov", "type": "Primary"}]}

{"bugzilla": {"description": "kernel: selinux: fix NULL-pointer dereference when hashtab allocation fails", "id": "2274568", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2274568"}, "csaw": false, "cvss3": {"cvss3_base_score": "4.4", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-476", "details": ["In the Linux kernel, the following vulnerability has been resolved:\nselinux: fix NULL-pointer dereference when hashtab allocation fails\nWhen the hash table slot array allocation fails in hashtab_init(),\nh->size is left initialized with a non-zero value, but the h->htable\npointer is NULL. This may then cause a NULL pointer dereference, since\nthe policydb code relies on the assumption that even after a failed\nhashtab_init(), hashtab_map() and hashtab_destroy() can be safely called\non it. Yet, these detect an empty hashtab only by looking at the size.\nFix this by making sure that hashtab_init() always leaves behind a valid\nempty hashtab when the allocation fails.", "A vulnerability was found in the Linux kernel, related to SELinux. This issue occurs when a hash table allocation fails during the hashtab_init() function. When this failure happens, the system leaves the hash table (h->size) initialized with a non-zero value, but the h->htable pointer remains null. This can result in a null pointer dereference when SELinux's policy database tries to use the hash table, relying on the assumption that it is valid. This situation can cause system crashes or unexpected behavior."], "name": "CVE-2021-47218", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Out of support scope", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Out of support scope", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Out of support scope", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2024-04-10T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2021-47218\nhttps://nvd.nist.gov/vuln/detail/CVE-2021-47218\nhttps://lore.kernel.org/linux-cve-announce/2024041006-CVE-2021-47218-cdc8@gregkh/T"], "statement": "The fix for this issue ensures that even in the case of allocation failure, hashtab_init() leaves behind a valid empty hash table, preventing the null pointer dereference and improving the stability of SELinux in this context\u200b", "threat_severity": "Moderate"}

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